1. Field of the Invention:
The present invention relates to an improvement in an electrified micrometer where measured size is indicated by a digital numeral display means.
2. Description of Prior Art:
In various kinds of measuring apparatus, digital indication of measured size has been widely adopted, for using digital indication, much of the skill and labor of reading the measured value can be eliminated. However, for such rather inexpensive apparatus as the micrometer, the adoption of the electrified digital indication should be made with rather low cost. Hitherto, several proposals have been made for converting a physical analog signal to motion to a digital signal. For example, a proposed system comprises an optical rotary encoder where rotation of a slit disk is detected by means of an LED and a phototransistor thereby issuing electric pulses corresponding to rotation of the slit disk; another proposed system comprises an electromagnetic encoder including a conversion head which is disposed so as to pick up magnetic flux of a rotary magnetic disk. These proposed systems have drawbacks of large bulk, high cost and high consumption of electric power, and therefore are not appropriate for use in micrometers which should be compact, usually small enough to be carried by hand and operated by a small dry battery stored therein.